The Port of Seattle's Harbor Island, mostly underwater at high tide in 2100.

Fish -- rather than crows and gulls -- pecking at the port's largest terminal.

Climate change will make Washington a warmer and wetter place, even while shrinking the snow packs that supply us with drinking water and salmon with robust streams. In Seattle, scientists say, the future holds water -- and lots of it -- with the rising of Puget Sound.

The University of Washington's Climate Impacts Group, tapped by the state to lend its expertise to climate change policy, predicted in January that sea levels in Puget Sound could rise by as much as 50 inches by 2100.

That's a worst-case scenario with grim economic repercussions.

It's enough to threaten large swaths of more than $1 billion in waterfront investments that the port has made in the past decade. And it's more than 3 feet above the sea-level rise that could be handled by the planned Alaskan Way sea wall's replacement.

Many have focused on how climate change is affected by transportation, which in 2004 was responsible for 45 percent of Washington's greenhouse gas emissions.

But a March report by the National Research Council turned the tables. It showed that across the U.S., ports and other transportation infrastructure -- the backbone of the trade economy -- would be among the hardest hit by climate change.

With so much at stake, what is being done?

Currently, the focus is on mitigation, or lessening the amounts of greenhouse gases produced. Scrambling back from the edge, so to speak -- even as some say the die has been cast because carbon dioxide stays in the atmosphere for more than a century.

Planning for a future shaped by climate change, however, is in its infancy.

The Port of Seattle, along with its neighboring ports in Tacoma and Everett, produced an inventory of maritime emissions in this region that included greenhouse gases. The Puget Sound ports came up with a voluntary maritime emissions-reduction plan, but their focus has been on diesel soot -- created by burning diesel fuel -- because of the cancer and asthma risks they present.

Locally in 2005, "the maritime industry as a whole produced 28 percent of (the region's) diesel particulate matter but only 2.6 percent of greenhouse gases, which was part of the reason our focus was most immediately on the diesel emissions," said Stephanie Jones, the Port of Seattle's senior manager of seaport environmental programs.

Much of what the seaports encourage does addressgreenhouse gas emissions tangentially, such as reducing engine idling and making operations more efficient. And it improves the bottom line, which helps get businesses on board. Some of it costs both the port and its partners, such as providing infrastructure for cruise ships to plug into the city's power grid rather than running their engines while at dock.

Other costs are borne by the private sector, such as switching to burning low-sulfur fuels while at dock, as APL and "K" Line did last year,or using a biodiesel blend to fuel cargo handling equipment, as SSA Marine did at Harbor Island's Terminal 18.

"We look at climate change in two halves, the first of which is what we can do to prevent our contributions to it," Jones said. "The second half is what we can do to adapt."

The port, submerged, is the second half.

No easy answers

Waterborne commerce built the communities along Puget Sound. But as forests fell and the cities grew, hills were leveled and their soil piled up to extend downtowns into the bays. Development clustered along the creeping coastline.

Now that coastline is threatening to creep back. Standing in its way are major commercial and industrial waterfronts such as those of Seattle, Tacoma and Olympia, and major supporting urban infrastructure as well as private property.

"We don't have the answers yet," Jones said. "You can't build a gate across the front of Elliott Bay."

Just a 2-foot rise in sea levels -- 2 inches beyond the upper bounds of the UW predictions for 2050 -- would inundate 56 square miles and affect at least 44,429 people, according to a state study that identified the area between Tacoma and Olympia as among the first that would be affected.

A recent state report found that "sea level rise will trigger an impulse by property owners and managers to 'protect' shorelines through armoring or diking." Such responses will make it more difficult for the coast-wide recovery: "Additional armoring directly threatens the ability of beaches and supporting shoreline processes to adapt to sea level rise" -- and removes critical habitat for a host of species, some of which are iconic for Washington, such as salmon.

That led a group advising the state -- composed of state officials and local governments, as well as tribal, business and academic leaders -- to "discourage or preclude additional armoring whenever alternatives exist."

Sometimes there may be little choice than to build up the coastline's armor.

Downtown Seattle is protected by the aging Alaskan Way sea wall, whose 1.4-mile length is due to be replaced at a likely cost of between $600 million and $800 million, said John Arnesen of the Seattle Department of Transportation.

The plan calls for a replacement of the sea wall, which can accommodate an 11-inch rise in the sea level, Arnesen said. He added that the city plan would be based on the best scientific data available when construction begins as early as 2012.

The complex future interplay of carbon dioxide and other greenhouse gas emissions, rising global temperatures, the expansion of the ocean as it warms, melting ice sheets and shifting earth crusts provides planners with a range of predictions for rising sea levels in the Puget Sound region by 2100. The UW's January study estimated a rise of between 6 and 50 inches.

The study identified the most likely sea-level rise as 6 inches by 2050 and 13 inches by 2100, but regardless of where the actual sea level is, other factors could push it up.

The particular threat is not just from inundation in a linear fashion, but from the increase in intensity from storms and increased flooding, said Ed Miles, the team leader of the UW Climate Impacts Group. Miles said storms now considered once-in-a-lifetime events will happen more often, possibly driving waves over Washington's coastal protections.

By 2100, major sections of the ports of Seattle and Tacoma are within coastal flood zones according to mid-range UW sea-level predictions; nearly all of the seaports are engulfed by the flood zones in their upper range projections.

The Port of Tacoma is raising the wharves it has in development to 22 feet above the mean low tide, which would clear the UW's highest sea- level rise predictions for 2100 by more than 3 feet.

"Commercial forces will drive these redevelopments before climate change will," said Port of Tacoma Chief Sustainable Development Officer Lou Paulsen. Seattle port staffers said they would also plan for sea-level rises when their terminals come up for redevelopment.

Taking rising sea levels into account when planning infrastructure is foremost amongst the recommendations made to the governor by the state report, which proposed revisions to the growth and shoreline management acts as well as its environmental review process.

The report also states "it is vital that state and local governments avoid putting facilities and residences into relatively undeveloped areas that are at significant risk to sea level rise."

Questioning whether or not to build in the face of rising seas is already happening in Olympia, the city worst hit by rising sea levels. Olympia's port peninsula is built on fill at low elevations, making it "vulnerable to substantial flooding" even under the UW's more conservative projections. City officials decided to relocate their planned City Hall from an area expected to be inundated, but are in negotiations to locate a children's museum on what is now port property in the projected flood zone.

Rick Dougherty, Olympia's project manager of the City Hall and children's museum locations, said the city is planning to raise the museum to anticipate rising waters. He noted that the neighboring sewage treatment plant, which serves Lacey, Olympia, Tumwater and Thurston County and, like the West Point Treatment Plant in Magnolia, could be threatened by wind-driven waves and storm surge, and the cost of relocating it could be $1 billion.

"It's going to be a big topic for a long time to come," Dougherty said.

Olympia's officials have said they would deal with the seas as a community rather than on a case-by-case basis.

"Adapting to climate change becomes a question of resources and risk tolerance," UW Climate Impacts Group policy specialist Lara Whitely Binder said. "How much are we willing to pay to preserve certain uses of coastal areas?"

It's not just the communities, but also the roads, rails and bridges that connect them that are also threatened by rising seas and surging storms.

"Inundation would affect our highways, but also erosion and landslides could be catastrophic," said Nancy Boyd, the state Department of Transportation's deputy state design engineer.

Boyd said the Transportation Department is in the earliest stages of conducting an inventory of existing infrastructure.

What needs money, how to allocate the funds and when to decide to pull back from development are all questions to be answered through community planning, said Whitely Binder.

If ice cap melting accelerates, sea levels could rise even higher -- complicating long-term planning. "There's always going to be a coastline," Whitely Binder said. "It's just a matter of where it is."